function reformat(s: string): string {
  const len = s.length
          let numArr = []
          let letterArr = []
          let res = ''
          for (let i = 0; i < len; i++) {
            if (/^[a-zA-Z]+$/.test(s[i])) {
              letterArr.push(s[i])
            }
            if (/^[0-9]+$/.test(s[i])) {
              numArr.push(s[i])
            }
          }
          if (Math.abs(numArr.length - letterArr.length) > 1) {
            return ''
          }
          if (numArr.length === letterArr.length) {
            for (let i = 0; i < numArr.length; i++) {
              res += numArr[i] + letterArr[i]
            }
          }
          if (numArr.length > letterArr.length) {
            res = numArr[0]
            for (let i = 0; i < letterArr.length; i++) {
              res += letterArr[i] + numArr[i + 1]
            }
          }
          if (numArr.length < letterArr.length) {
            res = letterArr[0]
            for (let i = 0; i < numArr.length; i++) {
              res += numArr[i] + letterArr[i + 1]
            }
          }
          return res
  };